Materials for electronic devices

ABSTRACT

The present application relates to a material comprising a monoarylamine of a formula (A) and a p-dopant of a defined formula. The present application further relates to the use of said material in an organic layer of an electronic device, the device preferably being an organic electroluminescent device (OLED).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application (under 35 U.S.C. §371)of PCT/EP2015/001940, filed Oct. 2, 2015, which claims benefit ofEuropean Application Nos. 14003629.4, filed Oct. 24, 2014, and15180257.6, filed Aug. 7, 2015, all of which are incorporated herein byreference in their entirety.

The present application relates to a material comprising a monoarylamineof a defined formula (A) and a complex of bismuth. The presentapplication further relates to the use of said material in an organiclayer of an electronic device, the device preferably being an organicelectroluminescent device (OLED).

The term “comprising” is understood in the context of this applicationto mean that further constituents or steps may be present. Theindefinite article “a” does not exclude the plural.

Electronic devices in the context of this application are understood tomean what are called organic electronic devices, which contain organicsemiconductor materials as functional materials.

The structure of OLEDs in which organic compounds are used as functionalmaterials is described, for example, in U.S. Pat. No. 4,539,507, U.S.Pat. No. 5,151,629, EP 0676461 and WO 98/27136. In general, the termOLEDs is understood to mean electronic devices which have one or morelayers comprising organic compounds and emit light on application ofelectrical voltage.

A great influence on the performance data of electronic devices ispossessed by layers having a hole-transporting function(hole-transporting layers), for example hole injection layers, holetransport layers and electron blocker layers.

The prior art discloses use of monoarylamines as materials forhole-transporting layers. Such monoarylamines are described, forexample, in JP 1995/053955, WO 2006/123667, JP 2010/222268, WO2012/034627, WO 2013/120577, WO 2014/015938 and WO 2014/015935.

In addition, the prior art discloses use of p-dopants in combinationwith hole transport materials in hole-transporting layers of OLEDs. Ap-dopant is understood here to mean a compound which, when added as aminor component to a main component, significantly increases theconductivity thereof.

p-Dopants known in the prior art are organic electron acceptorcompounds, for example7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (F4TCNQ). The priorart further discloses, as p-dopants, metal complexes of transition metalcations and main group metal cations, for example in WO 2011/33023 andWO 2013/182389.

The hole transport materials known in the prior art and the p-dopantsknown in the prior art result in a great variety of potentially possiblecombinations. Of these, only a few are disclosed in the prior art.Mention may be made here by way of example of the combination of maingroup metal complexes as p-dopants with tetraamines, for example2,2′,7,7′-tetra(N,N-di-p-tolyl)amino-9,9-spirobifluorene in the holetransport layer of an OLED. This is disclosed in WO 2013/182389. Afurther example from the prior art is the combination of F4TCNQ withmonoarylamines, for example tris-para-biphenylamine in the holetransport layer of an OLED. This is disclosed in WO 2013/135352.

However, OLEDs comprising these materials in the hole transport layerare in need of improvement in relation to lifetime and efficiency.

There is additionally a need for p-dopants capable of efficiently dopinghole transport materials having a low-lying HOMO, especially thosehaving a HOMO within the range from −5.0 to −5.4 eV, such that it ispossible to obtain dopant-hole transport material combinations havingboth a suitable conductivity and a low HOMO energy level. HOMO energiesare determined here by the method specified in the working examples.Suitable and preferred conductivities are in the range from 10⁻⁴ S/m to10⁻³ S/m, determined by the method specified in the working examples.The use of hole transport materials having a low-lying HOMO is highlydesirable because this dispenses with the necessity of inserting afurther layer having a low HOMO between hole transport layer andemitting layer. This enables a simpler construction of the OLED andhence a more efficient production process. If a further layer isinserted between hole transport layer and emitting layer, it is possiblein the desired case of a hole transport layer having a low HOMO to avoida hole barrier and hence a voltage drop between the hole transport layerand the emitting layer by virtue of the HOMO of the hole transport layerbeing no higher than the HOMO of the layer between the hole transportlayer and emitting layer. This is possible, for example, through the useof the same material in the hole transport layer and the further layerbetween the hole transport layer and emitting layer.

There is additionally a need for hole transport material-dopantcombinations having only a low absorption in the visible region (VISregion). The p-dopants known in the prior art, for example NDP-2(commercially available from Novaled AG) or molybdenum oxide dopants, incombination with the standard hole transport materials have absorptionsin the VIS region. The absence of significant absorption bands in theVIS region is highly desirable since absorptions in the VIS regionaffect the emission characteristics of the OLEDs and worsen theefficiency thereof.

In studies of possible combinations of p-dopants and hole transportmaterials for use in hole transport layers, it has now been found that,unexpectedly, a material comprising a monoarylamine of a specificformula (A) and a bismuth complex gives excellent values compared to theprior art in relation to lifetime and efficiency. In addition, theinventive material has lower leakage currents when used in OLEDs thanmaterials according to the prior art. Without being bound to thistheory, this may be caused by a lower lateral conductivity of the dopedlayer of the OLED. With pixels in displays becoming ever smaller,leakage currents are a great problem since they can lead to crosstalkbetween the pixels. The avoidance thereof is therefore desirable. Yetanother feature of the inventive material is only a low absorption bandin the VIS region. Yet another feature is that it is possible with theinventive material, because of the low HOMO position of themonoarylamine, to produce OLEDs which need not have any additional layerbetween the hole transport layer comprising the inventive material andthe emitting layer and can therefore be produced in a more efficientmanner.

The present application therefore provides a material comprising acompound A of a formula (A)

where the variables that occur are:

-   Z is CR¹;-   Ar¹ is the same or different at each instance and is an aromatic    ring system which has 6 to 30 aromatic ring atoms and may be    substituted by one or more R¹ radicals, or a heteroaromatic ring    system which has 5 to 30 aromatic ring atoms and may be substituted    by one or more R¹ radicals;-   R¹ is the same or different at each instance and is selected from H,    D, F, C(═O)R², CN, Si(R²)₃, P(═O)(R²)₂, OR², S(═O)R², S(═O)₂R²,    straight-chain alkyl or alkoxy groups having 1 to 20 carbon atoms,    branched or cyclic alkyl or alkoxy groups having 3 to 20 carbon    atoms, alkenyl or alkynyl groups having 2 to 20 carbon atoms,    aromatic ring systems having 6 to 30 aromatic ring atoms, and    heteroaromatic ring systems having 5 to 30 aromatic ring atoms;    where two or more R¹ radicals may be joined to one another and may    form a ring; where the alkyl, alkoxy, alkenyl and alkynyl groups    mentioned and the aromatic ring systems and heteroaromatic ring    systems mentioned may each be substituted by one or more R²    radicals; and where one or more CH₂ groups in the alkyl, alkoxy,    alkenyl and alkynyl groups mentioned may be replaced by —R²C═CR²—,    Si(R²)₂, C═O, C═NR², —C(═O)O—, —C(═O)NR²—, P(═O)(R²), —O—, —S—, SO    or SO₂;-   R² is the same or different at each instance and is selected from H,    D, F, CN, alkyl groups having 1 to 20 carbon atoms, aromatic ring    systems having 6 to 30 aromatic ring atoms and heteroaromatic ring    systems having 5 to 30 aromatic ring atoms; where two or more R²    radicals may be joined to one another and may form a ring; and where    the alkyl groups, aromatic ring systems and heteroaromatic ring    systems mentioned may be substituted by F or ON;    and a compound P which is a complex of bismuth.

A BRIEF DESCRIPTION OF THE FIGURE

FIG. 1 illustrates the values obtained for the specific conductivityagainst the proportion by volume of the dopant, in each case for thefollowing host/dopant combinations: i) BipFBz (═BiC1):DA1; ii) BipFBz(═BiC1):MA1; iii) BiC DA1; and iv) BiC:MA1. Inventive combinations areii) and iv).

An aromatic ring system in the context of this invention contains 6 to60 carbon atoms in the ring system. It does not comprise any heteroatomsas aromatic ring atoms. An aromatic ring system in the context of thisinvention therefore does not contain any heteroaryl groups. An aromaticring system in the context of this invention shall be understood to meana system which does not necessarily contain only aryl groups but inwhich it is also possible for a plurality of aryl groups to be bonded bya single bond or by a non-aromatic unit, for example one or moreoptionally substituted C, Si, N, O or S atoms. In this case, thenonaromatic unit comprises preferably less than 10% of the atoms otherthan H, based on the total number of atoms other than H in the system.For example, systems such as 9,9′-spirobifluorene, 9,9′-diarylfluorene,triarylamine, diaryl ethers and stilbene are also to be regarded asaromatic ring systems in the context of this invention, and likewisesystems in which two or more aryl groups are joined, for example, by alinear or cyclic alkyl, alkenyl or alkynyl group or by a silyl group. Inaddition, systems in which two or more aryl groups are joined to oneanother via single bonds are also to be regarded as aromatic ringsystems in the context of this invention, for example systems such asbiphenyl and terphenyl.

A heteroaromatic ring system in the context of this invention contains 5to 60 aromatic ring atoms, at least one of which is a heteroatom. Theheteroatoms of the heteroaromatic ring system are preferably selectedfrom N, O and/or S. A heteroaromatic ring system corresponds to theabovementioned definition of an aromatic ring system, but has at leastone heteroatom as one of the aromatic ring atoms. In this way, itdiffers from an aromatic ring system in the sense of the definition ofthe present application, which, according to this definition, cannotcontain any heteroatom as aromatic ring atom.

An aryl group in the context of this invention contains 6 to 40 aromaticring atoms of which none is a heteroatom. An aryl group in the contextof this invention is understood to mean either a simple aromatic cycle,i.e. benzene, or a fused aromatic polycycle, for example naphthalene,phenanthrene or anthracene. A fused aromatic polycycle in the context ofthe present application consists of two or more simple aromatic cyclesfused to one another. Fusion between cycles is understood here to meanthat the cycles share at least one edge with one another.

A heteroaryl group in the context of this invention contains 5 to 40aromatic ring atoms of which at least one is a heteroatom. Theheteroatoms of the heteroaryl group are preferably selected from N, Oand S. A heteroaryl group in the context of this invention is understoodto mean either a simple heteroaromatic cycle, for example pyridine,pyrimidine or thiophene, or a fused heteroaromatic polycycle, forexample quinoline or carbazole. A fused heteroaromatic polycycle in thecontext of the present application consists of two or more simpleheteroaromatic cycles fused to one another. Fusion between cycles isunderstood to mean that the cycles share at least one edge with oneanother.

An aromatic ring system having 6 to 40 aromatic ring atoms or aheteroaromatic ring system having 5 to 40 aromatic ring atoms areespecially understood to mean groups derived from the groups mentionedabove under aryl groups and heteroaryl groups, and from biphenyl,terphenyl, quaterphenyl, fluorene, spirobifluorene, dihydrophenanthrene,dihydropyrene, tetrahydropyrene, indenofluorene, truxene, isotruxene,spirotruxene, spiroisotruxene, indenocarbazole, or from combinations ofthese groups.

An aryl or heteroaryl group, each of which may be substituted by theabovementioned radicals and which may be joined to the aromatic orheteroaromatic system via any desired positions, is especiallyunderstood to mean groups derived from benzene, naphthalene, anthracene,phenanthrene, pyrene, dihydropyrene, chrysene, perylene, triphenylene,fluoranthene, benzanthracene, benzophenanthrene, tetracene, pentacene,benzopyrene, furan, benzofuran, isobenzofuran, dibenzofuran, thiophene,benzothiophene, isobenzothiophene, dibenzothiophene, pyrrole, indole,isoindole, carbazole, pyridine, quinoline, isoquinoline, acridine,phenanthridine, benzo-5,6-quinoline, benzo-6,7-quinoline,benzo-7,8-quinoline, phenothiazine, phenoxazine, pyrazole, indazole,imidazole, benzimidazole, naphthimidazole, phenanthrimidazole,pyndimidazole, pyrazinimidazole, quinoxalinimidazole, oxazole,benzoxazole, naphthoxazole, anthroxazole, phenanthroxazole, isoxazole,1,2-thiazole, 1,3-thiazole, benzothiazole, pyridazine, benzopyridazine,pyrimidine, benzopyrimidine, quinoxaline, pyrazine, phenazine,naphthyridine, azacarbazole, benzocarboline, phenanthroline,1,2,3-triazole, 1,2,4-triazole, benzotriazole, 1,2,3-oxadiazole,1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole,1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, 1,3,5-triazine,1,2,4-triazine, 1,2,3-triazine, tetrazole, 1,2,4,5-tetrazine,1,2,3,4-tetrazine, 1,2,3,5-tetrazine, purine, pteridine, indolizine andbenzothiadiazole.

In the context of the present invention, a straight-chain alkyl grouphaving 1 to 20 carbon atoms and a branched or cyclic alkyl group having3 to 20 carbon atoms and an alkenyl or alkynyl group having 2 to 20carbon atoms in which individual hydrogen atoms or CH₂ groups may alsobe replaced by the groups mentioned above in the definition of theradicals are preferably understood to mean the methyl, ethyl, n-propyl,i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl,s-pentyl, cyclopentyl, neopentyl, n-hexyl, cyclohexyl, neohexyl,n-heptyl, cycloheptyl, n-octyl, cyclooctyl, 2-ethylhexyl,trifluoromethyl, pentafluoroethyl, 2,2,2-trifluoroethyl, ethenyl,propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl,heptenyl, cycloheptenyl, octenyl, cyclooctenyl, ethynyl, propynyl,butynyl, pentynyl, hexynyl or octynyl radicals.

An alkoxy or thioalkyl group having 1 to 20 carbon atoms in whichindividual hydrogen atoms or CH₂ groups may also be replaced by thegroups mentioned above in the definition of the radicals is preferablyunderstood to mean methoxy, trifluoromethoxy, ethoxy, n-propoxy,i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy, n-pentoxy, s-pentoxy,2-methylbutoxy, n-hexoxy, cyclohexyloxy, n-heptoxy, cycloheptyloxy,n-octyloxy, cyclooctyloxy, 2-ethylhexyloxy, pentafluoroethoxy,2,2,2-trifluoroethoxy, methylthio, ethylthio, n-propylthio,i-propylthio, n-butylthio, butylthio, s-butylthio, t-butylthio,n-pentylthio, s-pentylthio, n-hexylthio, cyclohexylthio, n-heptylthio,cycloheptylthio, n-octylthio, cyclooctylthio, 2-ethyl hexylthio,trifluoromethylthio, pentafluoroethylthio, 2,2,2-trifluoroethylthio,ethenylthio, propenylthio, butenylthio, pentenylthio, cyclopentenylthio,hexenylthio, cyclohexenylthio, heptenylthio, cycloheptenylthio,octenylthio, cyclooctenylthio, ethynylthio, propynylthio, butynylthio,pentynylthio, hexynylthio, heptynylthio or octynylthio.

The wording that two or more radicals together may form a ring, in thecontext of the present application, shall be understood to mean, interalia, that the two radicals are joined to one another by a chemicalbond. In addition, however, the abovementioned wording shall also beunderstood to mean that, if one of the two radicals is hydrogen, thesecond radical binds to the position to which the hydrogen atom wasbonded, forming a ring.

The compound A preferably has a low-lying HOMO, more preferably a HOMOwithin the range from −5.0 to −5.4 eV, most preferably a HOMO within therange from −5.1 to −5.3 eV.

The compound A is a monoarylamine. A monoarylamine is understood here tomean a compound having a single arylamino group and not more than one.According to the invention, the compound A is a monotriarylaminocompound, meaning that it has a single triarylamino group. The term“triarylamino group” is preferably also understood to mean compoundscontaining heteroaryl groups bonded to the amino nitrogen. Furtherpreferably, the compound A has a single amino group. It should be notedthat, according to the definition of the present application, carbazolegroups do not count as arylamino groups or amino groups.

According to a further preferred embodiment of the invention, thecompound A does not contain a fused aryl group having more than 10aromatic ring atoms nor a fused heteroaryl group having more than 14aromatic ring atoms.

Ar¹ is preferably the same or different at each instance and is anaromatic ring system which has 6 to 24 aromatic ring atoms and may besubstituted by one or more R¹ radicals, or a heteroaromatic ring systemwhich has 5 to 24 aromatic ring atoms and may be substituted by one ormore R¹ radicals.

Preferably, at least one Ar¹ group in the compound of the formula (A) isa group which is optionally substituted by one or more R¹ radicals andis selected from phenyl, biphenyl, terphenyl, quaterphenyl, naphthyl,phenanthryl, fluoranthenyl, fluorenyl, indenofluorenyl,spirobifluorenyl, furanyl, benzofuranyl, isobenzofuranyl,dibenzofuranyl, thiophenyl, benzothiophenyl, isobenzothiophenyl,dibenzothiophenyl, indolyl, isoindolyl, carbazolyl, indolocarbazolyl,indenocarbazolyl, pyridyl, quinolinyl, isoquinolinyl, acridyl,phenanthridyl, benzimidazolyl, pyrimidyl, pyrazinyl and triazinyl;particular preference among these is given to phenyl, biphenyl,terphenyl, quaterphenyl, naphthyl, phenanthryl, fluoranthenyl,fluorenyl, indenofluorenyl, spirobifluorenyl, clibenzofuranyl,dibenzothiophenyl, carbazolyl, acridyl and phenanthridyl.

R¹ is preferably the same or different at each instance and is selectedfrom H, D, F, CN, Si(R²)₃, straight-chain alkyl or alkoxy groups having1 to 10 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3to 10 carbon atoms, aromatic ring systems having 6 to 40 aromatic ringatoms and heteroaromatic ring systems having 5 to 40 aromatic ringatoms; where the alkyl and alkoxy groups mentioned, the aromatic ringsystems mentioned and the heteroaromatic ring systems mentioned may eachbe substituted by one or more R² radicals; and where one or more CH₂groups in the alkyl or alkoxy groups mentioned may be replaced by —C≡C—,—R²C═CR²—, Si(R²)₂, C═O, C═NR², —O—, —S—, —C(═O)O— or —C(═O)NR²—.

R¹ is more preferably the same or different at each instance and isselected from H, F, CN, straight-chain alkyl or alkoxy groups having 1to 8 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3 to8 carbon atoms, aromatic ring systems having 6 to 24 aromatic ringatoms, and heteroaromatic ring systems having 5 to 24 aromatic ringatoms, where said alkyl groups, said aromatic ring systems and saidheteroaromatic ring systems may each be substituted by one or more R²radicals. Particular preference is given among these to H, F, methyl,ethyl, tert-butyl, and phenyl.

More preferably, the compound of the formula (A) contains no R¹ radicalthat is not H, exactly one R¹ radical that is not H, or exactly two R¹radicals that are not H.

Preferably, at least one Ar¹ group, more preferably all the Ar¹ groups,in the compound of the formula (A) are the same or different at eachinstance and are selected from the following groups, each of which maybe substituted by one or more R¹ radicals at any of the unsubstitutedpositions shown:

Preferred embodiments of compound A are the following compounds:

Preparation processes for-compounds of the formula (A) are known in theprior art. In particular, the person skilled in the art may makereference to the disclosure of document WO 2012/034627.

The compound P is a p-dopant in the sense of the abovementioneddefinition. Without being bound to this theory, it is assumed that thecompound P is a Lewis acid which, when present mixed with the compoundA, forms a complex with the compound A. The compound A acts here as aLewis base. Without being bound to this theory, the complex is formed byvirtue of a free electron pair in compound A interacting with thebismuth metal atom of compound P.

The compound P may be a mononuclear complex of bismuth, a binuclearcomplex of bismuth or a polynuclear complex of bismuth. It is possiblethat the compound P is a mononuclear complex of bismuth if it is presentin the gas phase and a polynuclear complex of bismuth if it is in thesolid phase. This means that the compound P may polymerize ordepolymerize according to the state of matter.

The complex of bismuth is preferably a complex of bismuth in the (II),(Ill) or (V) oxidation state. It is more preferably a complex of bismuthin the (III) oxidation state.

Preferably, the complex of bismuth has at least one ligand L which is anorganic compound. The ligand L is preferably selected from monodentate,bidentate and tridentate ligands, more preferably from monodentateligands. Further preferably, the ligand L is negatively charged,preferably triply, doubly or singly negatively charged, more preferablysingly negatively charged.

The group of the ligand L that binds to the bismuth atom is preferablyselected from carboxylic acid groups, thiocarboxylic acid groups, inparticular thiolic acid groups, thionic acid groups and dithiolic acidgroups, carboxamide groups and carboximide groups, more preferably fromcarboxylic acid groups.

Preferably, the ligand L corresponds to one of the following formulae(L-I), (L-II), (L-III) and (L-IV)

where:W is selected from carboxylic acid groups; thiocarboxylic acid groups,in particular thiolic acid groups, thionic acid groups and dithiolicacid groups; carboxamide groups and carboximide groups, more preferablyfrom carboxylic acid groups;U is the same or different at each instance and is selected from N andCR³ if no W group is bonded thereto, and U is C when a W group is bondedthereto; andR³ is the same or different at each instance and is selected from H, D,F, Cl, Br, I, CN, NO₂, CF₃, straight-chain alkyl or alkoxy groups having1 to 20 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3to 20 carbon atoms, alkenyl or alkynyl groups having 2 to 20 carbonatoms, aromatic ring systems having 6 to 40 aromatic ring atoms, andheteroaromatic ring systems having 5 to 40 aromatic ring atoms; wherethe alkyl, alkoxy, alkenyl and alkynyl groups mentioned and the aromaticring systems and heteroaromatic ring systems mentioned may each besubstituted by one or more R⁴ radicals; and where one or more CH₂ groupsin the alkyl, alkoxy, alkenyl and alkynyl groups mentioned may bereplaced by —R⁴C═CR⁴—, —C≡C—, Si(R⁴)₂, C═O, C═NR⁴, —C(═O)O—, —C(═O)NR⁴—,P(═O)(R⁴), —O—, —S—, SO or SO₂; andR⁴ is the same or different at each instance and is selected from H, D,F, Cl, CN, NO₂, alkyl groups having 1 to 20 carbon atoms, aromatic ringsystems having 6 to 40 aromatic ring atoms and heteroaromatic ringsystems having 5 to 40 aromatic ring atoms; where two or more R⁴radicals may be joined to one another and may form a ring; and where thealkyl groups, aromatic ring systems and heteroaromatic ring systemsmentioned may be substituted by F, Cl, CN and NO₂; andR⁵ is the same or different at each instance and is selected from H, D,F, C(═O)R⁴, CN, Si(R⁴)₃, P(═O)(R⁴)₂, OR⁴, S(═O)R⁴, S(═O)₂R⁴,straight-chain alkyl or alkoxy groups having 1 to 20 carbon atoms,branched or cyclic alkyl or alkoxy groups having 3 to 20 carbon atoms,alkenyl or alkynyl groups having 2 to 20 carbon atoms, aromatic ringsystems having 6 to 40 aromatic ring atoms, and heteroaromatic ringsystems having 5 to 40 aromatic ring atoms; where two or more R¹radicals may be joined to one another and may form a ring; where thealkyl, alkoxy, alkenyl and alkynyl groups mentioned and the aromaticring systems and heteroaromatic ring systems mentioned may each besubstituted by one or more R⁴ radicals; and where one or more CH₂ groupsin the alkyl, alkoxy, alkenyl and alkynyl groups mentioned may bereplaced by —R⁴C═CR⁴—, —C≡C—, Si(R⁴)₂, C═O, C═NR⁴, —C(═O)O—, —C(═O)NR⁴—,P(═O)(R⁴), —O—, —S—, SO or SO₂; andR⁶ is the same or different at each instance and is selected from H, D,F, Cl, Br, I, CN, NO₂, CF₃, straight-chain alkyl or alkoxy groups having1 to 20 carbon atoms, branched or cyclic alkyl or alkoxy groups having 3to 20 carbon atoms, alkenyl or alkynyl groups having 2 to 20 carbonatoms, aromatic ring systems having 6 to 40 aromatic ring atoms, andheteroaromatic ring systems having 5 to 40 aromatic ring atoms; wherethe alkyl, alkoxy, alkenyl and alkynyl groups mentioned and the aromaticring systems and heteroaromatic ring systems mentioned may each besubstituted by one or more R⁴ radicals; and where one or more CH₂ groupsin the alkyl, alkoxy, alkenyl and alkynyl groups mentioned may bereplaced by —R⁴C═CR⁴—, —C≡C—, Si(R⁴)₂, C═O, C═NR⁴, —C(═O)O—, —C(═O)NR⁴—,P(═O)(R⁴), —O—, —S—, SO or SO₂.

Preferably, in each of the formulae (L-I) to (L-III), at least one R³group is present, selected from F, Cl, Br, I, CN, NO₂ and alkyl groupswhich have 1 to 20 carbon atoms and at least one substituent selectedfrom F, Cl, CN and NO₂. Among the groups mentioned, particularpreference is given to F, Cl, CN and CF₃.

More preferably, one, two, three, four or five R³ groups of this kindare present, even more preferably three, four or five, most preferablythree or five.

Preferably, in formula (L-IV), at least one R⁶ group is present,selected from F, Cl, Br, I, CN, NO₂ and alkyl groups which have 1 to 20carbon atoms and at least one substituent selected from F, Cl, CN andNO₂.

Among the groups mentioned, particular preference is given to F, Cl, CNand CF₃. More preferably, one, two or three R⁶ groups of this kind arepresent, most preferably three.

Preferred ligands L are selected from fluorinated benzoic acidderivatives, fluorinated or non-fluorinated phenylacetic acidderivatives and fluorinated or non-fluorinated acetic acid derivatives.

Examples of preferred fluorinated benzoic acid derivatives are:2-(trifluoromethyl)benzoic acid; 3,5-difluorobenzoic acid;3-hydroxy-2,4,6-triiodobenzoic acid; 3-fluoro-4-methylbenzoic acid;3-(trifluoromethoxy)benzoic acid; 4-(trifluoromethoxy)benzoic acid;4-chloro-2,5-difluorobenzoic acid; 2-chloro-4,5-difluorobenzoic acid;2,4,5-trifluorobenzoic acid; 2-fluorobenzoic acid; 4-fluorobenzoic acid;2,3,4-trifluorobenzoic acid; 2,3,5-trifluorobenzoic acid;2,3-difluorobenzoic acid; 2,4-bis(trifluoromethyl)benzoic acid;2,4-difluorobenzoic acid; 2,5-difluorobenzoic acid;2,6-bis(trifluoromethyl)benzoic acid; 2,6-difluorobenzoic acid;2-chloro-6-fluorobenzoic acid; 2-fluoro-4-(trifluoromethyl)benzoic acid;2-fluoro-5-(trifluoromethyl)benzoic acid;2-fluoro-6-(trifluoromethyl)benzoic acid; 3,4,5-trifluorobenzoic acid;3,4-difluorobenzoic acid; 3,5-bis(trifluoromethyl)benzoic acid;3-(trifluoromethyl)benzoic acid; 3-chloro-4-fluorobenzoic acid;3-fluoro-5-(trifluoromethyl)benzoic acid; 3-fluorobenzoic acid;4-fluoro-2-(trifluoromethyl)benzoic acid;4-fluoro-3-(trifluoromethyl)benzoic acid; 5-fluoro-2-methylbenzoic acid;2-(trifluoromethoxy)benzoic acid; 2,3,5-trichlorobenzoic acid;4-(trifluoromethyl)benzoic acid; pentafluorobenzoic acid; and2,3,4,5-tetrafluorobenzoic acid.

Examples of fluorinated or non-fluorinated phenylacetic acid derivativesare: 2-fluorophenylacetic acid; 3-fluorophenylacetic acid;4-fluorophenylacetic acid; 2,3-difluorophenylacetic acid;2,4-difluorophenylacetic acid; 2,6-difluorophenylacetic acid;3,4-difluorophenylacetic acid; 3,5-difluorophenylacetic acid;pentafluoro-phenylacetic acid; 2-chloro-6-fluorophenylacetic acid;2-chloro-3,6-difluorophenylacetic acid;3-chloro-2,6-difluorophenylacetic acid; 3-chloro-4-fluorophenylaceticacid; 5-chloro-2-fluorophenylacetic acid; 2,3,4-trifluorophenylaceticacid; 2,3,5-trifluorophenylacetic acid; 2,3,6-trifluorophenylaceticacid; 2,4,5-trifluorophenylacetic acid; 2,4,6-trifluorophenylaceticacid; 3,4,5-trifluorophenylacetic acid; 3-chloro-2-fluorophenylaceticacid; 6-fluorophenylacetic acid; 4-chloro-2-fluorophenylacetic acid;2-chloro-4-fluorophenylacetic acid.

Examples of fluorinated or non-fluorinated acetic acid derivatives are:difluoroacetic acid; trifluoroacetic acid; chlorodifluoroacetic acid;(3-chlorophenyl)difluoroacetic acid; (3,5-difluorophenyl)difluoroaceticacid; (4-butylphenyl) difluoroacetic acid;(4-tert-butylphenyl)difluoroacetic acid; (3,4-dimethylphenyl)difluoroacetic acid; (3-chloro-4-fluorophenyl)-difluoroaceticacid; (4-chlorophenyl)-difluoroacetic acid;2-biphenyl-3′,5′-difluoroacetic acid; 3-biphenyl-3′,5′-difluoroaceticacid; 4-biphenyl-3′,5′ difluoroacetic acid;2-biphenyl-3′,4′-difluoroacetic acid; 3-biphenyl-3′,4′-difluoroaceticacid; 4-biphenyl-3′,4′-difluoroacetic acid and 2,2-difluoropropionicacid and higher homologues thereof.

The compounds mentioned in deprotonated form in the above list may alsobe present in protonated form in accordance with the invention. They arepreferably in deprotonated form. The compounds mentioned in protonatedform in the above list may also be present in deprotonated form, whichis preferred in accordance with the invention.

The material of the invention may contain further compounds. Itpreferably contains essentially exclusively exactly one compound A andexactly one compound P. If further compounds are present, these arepreferably compounds according to formula (A). In one possibleembodiment of the invention, exactly two different compounds A andexactly one compound P are present in the material of the invention.

The compound P is preferably present as a dopant in the material of theinvention. It is preferable that the material of the invention containsthe compound P in a concentration of 0.1% to 30%, more preferably 0.5%to 25%, even more preferably 5% to 20%.

Percentages in the context of the present application are stated suchthat they mean % by volume in the case of gas phase deposition and % byweight in the case of application from the liquid phase.

The material of the invention is preferably in the form of a thin layer,more preferably of a functional layer of an electronic device. Thepresent invention therefore also provides a layer, preferably asemiconductor layer, comprising the material of the invention.

The layer comprising the material of the invention preferably has athickness of 1 to 500 nm, more preferably of 5 to 300 nm and mostpreferably of 8 to 250 nm. It is preferably used as hole-transportinglayer in an electronic device, preferably of an OLED, as laid out indetail further down.

The layer comprising the material of the invention preferably has aspecific conductivity between 10⁻² S/m and 10⁻⁵ S/m, more preferablybetween 10⁻³ S/m and 10⁻⁴ S/m, the latter being determined as specifiedin the working examples.

The material of the invention can be applied in the form of a layer fromthe gas phase, for example by means of the OVPD (organic vapour phasedeposition) method or with the aid of carrier gas sublimation. In thiscase, the materials are applied at a pressure between 10⁻⁵ mbar and 1bar. A special case of this method is the OVJP (organic vapour jetprinting) method, in which the materials are applied directly by anozzle and thus structured (for example M. S. Arnold et al., Appl. Phys.Lett. 2008, 92, 053301). Alternatively, the material can also beproduced from the liquid phase, for example by spin-coating, or by anyprinting method, for example screen printing, flexographic printing,nozzle printing or offset printing, preferably LITI (light-inducedthermal imaging, thermal transfer printing) or inkjet printing.

For the processing of the material of the invention from the liquidphase, for example by the abovementioned methods, formulations arerequired. These formulations may, for example, be solutions, dispersionsor emulsions. For this purpose, it may be preferable to use mixtures oftwo or more solvents. Suitable and preferred solvents are, for example,toluene, anisole, o-, m- or p-xylene, methyl benzoate, mesitylene,tetralin, veratrole, THF, methyl-THF, THP, chlorobenzene, dioxane,phenoxytoluene, especially 3-phenoxytoluene, (−)-fenchone,1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene,1-methylnaphthalene, 2-methylbenzothiazole, 2-phenoxyethanol,2-pyrrolidinone, 3-methylanisole, 4-methylanisole, 3,4-dimethylanisole,3,5-dimethylanisole, acetophenone, α-terpineol, benzothiazole, butylbenzoate, cumene, cyclohexanol, cyclohexanone, cyclohexylbenzene,decalin, dodecylbenzene, ethyl benzoate, indane, methyl benzoate, NMP,p-cymene, phenetole, 1,4-diisopropylbenzene, dibenzyl ether, diethyleneglycol butyl methyl ether, triethylene glycol butyl methyl ether,diethylene glycol dibutyl ether, triethylene glycol dimethyl ether,diethylene glycol monobutyl ether, tripropylene glycol dimethyl ether,tetraethylene glycol dimethyl ether, 2-isopropyl naphthalene,pentylbenzene, hexylbenzene, heptylbenzene, octylbenzene,1,1-bis(3,4-dimethylphenyl)ethane or mixtures of these solvents.

The invention therefore further provides a formulation, especially asolution, dispersion or emulsion, comprising the material of theinvention and at least one solvent, preferably an organic solvent. Theway in which such a formulation, especially such solutions, can beprepared is known to those skilled in the art and is described, forexample, in WO 2002/072714, WO 2003/019694 and the literature citedtherein.

In the case of gas phase deposition, both compound P and compound A arecoevaporated, preferably from different vapour deposition sources, anddeposited as a layer. In the case of application from the liquid phase,the compound P and the compound A are dissolved in solvent and thenapplied by means of the abovementioned printing techniques. The layercomprising the material of the invention is finally obtained byevaporating the solvent.

The present application therefore also provides a process for producinga layer comprising the material of the invention, characterized in thatcompound A and compound P are applied together from the gas phase, or inthat a formulation comprising the material of the invention is appliedfrom the liquid phase.

The material of the invention is suitable for use in electronic devices,preferably selected from the group consisting of organicelectroluminescent devices (OLEDs), organic integrated circuits (OLECs),organic field-effect transistors (OFETs), organic thin-film transistors(OTFTs), organic light-emitting transistors (OLETs), organic solar cells(OSCs), organic optical detectors, organic photoreceptors, organicfield-quench devices (OFQDs), organic light-emitting electrochemicalcells (OLECs), and organic laser diodes (O-lasers).

This material may be used in different functions. Preference is given tothe use of the material in a hole transport layer, especially in a holeinjection layer, a hole transport layer, or an exciton blocker layer.The above-described use of the material likewise forms part of thesubject-matter of the invention.

A hole transport layer according to the present application in a broadersense is a layer having a hole-transporting function between the anodeand emitting layer. Specifically, a hole transport layer according tothe present application is a layer which has a hole-transportingfunction, is present between the anode and emitting layer and is neithera hole injection layer nor an electron blocker layer nor an excitonblocker layer.

The invention further provides an electronic device comprising thematerial of the invention, preferably in the form of a layer. Thiselectronic device is preferably selected from the abovementioneddevices. More preferably, the electronic device is an OLED comprisinganode, cathode and at least one emitting layer, characterized in that atleast one layer, preferably a hole transport layer, comprises thematerial of the invention.

Apart from the cathode, anode and emitting layer, the OLED preferablycomprises still further functional layers. These are selected, forexample, from in each case one or more hole injection layers, holetransport layers, hole blocker layers, electron transport layers,electron injection layers, electron blocker layers, exciton blockerlayers, interlayers, charge generation layers (IDMC 2003, Taiwan;Session 21 OLED (5), T. Matsumoto, T. Nakada, J. Endo, K. Mori, N.Kawamura, A. Yokoi, J. Kido, Multiphoton Organic EL Device Having ChargeGeneration Layer) and/or organic or inorganic p/n junctions.

The sequence of the layers of the OLED comprising the material of theinvention is preferably as follows:

-   -   anode    -   hole injection layer    -   hole transport layer    -   optionally further hole transport layer    -   optionally electron blocker layer    -   emitting layer    -   optionally hole blocker layer    -   electron transport layer    -   electron injection layer    -   cathode.

However, it is not necessary for all the layers mentioned to be present,and further layers may additionally be present. It is preferable thatthe material of the invention, in the above layer sequence, is presentin one or more layers selected from hole injection layer and holetransport layer, more preferably in a hole injection layer.

Particular preference is given to the following layer sequence:

-   -   anode    -   hole injection layer    -   hole transport layer    -   optionally electron blocker layer    -   emitting layer    -   electron transport layer    -   electron injection layer    -   cathode.

However, it is not necessary for all the layers mentioned to be present,and further layers may additionally be present. It is preferable thatthe material of the invention, in the above layer sequence, is presentin one or more layers selected from hole injection layer and holetransport layer, more preferably in a hole injection layer.

The OLED of the invention may comprise several emitting layers. Morepreferably, these emission layers in this case have several emissionmaxima between 380 nm and 750 mm overall, such that the overall resultis white emission; in other words, various emitting compounds which mayfluoresce or phosphoresce and which emit blue, yellow, green, orange orred light are used in the emitting layers. Especially preferred arethree-layer systems, i.e. systems having three emitting layers, wherethe three layers show blue, green and orange or red emission (for thebasic construction see, for example, WO 2005/011013).

Preferably, the OLED comprises the material of the invention in ahole-transporting layer disposed between the anode and emitting layer,with one or more further layers preferably present between the layercomprising the material of the invention and the emitting layer.Preferably, these further layers are hole transport layers, morepreferably electron blocker layers. The further layers mentioned may bep-doped or non-p-doped; preferably they are non-p-doped.

In a preferred embodiment of the invention, the HOMO levels of thehole-transporting layer (HTL) and the layer between thehole-transporting layer and emitting layer (EBL) meet the followingcondition:

HOMO(HTL)<=HOMO(EBL).

In this way, it is possible to avoid a hole barrier and hence a voltagedrop between the hole transport layer and the emitting layer. This isadvantageously possible, for example, through the use of the samematerial in the hole transport layer and the further layer between thehole transport layer and emitting layer.

However, it may also be preferable that the material of the invention isdisposed in a hole-transporting layer directly adjoining the emittinglayer.

The hole transport layers disposed between the layer comprising thematerial of the invention and the emitting layer preferably comprise oneor more identical or different compounds of the formula (A), preferablyidentical compounds of the formula (A). However, they may also compriseother compounds. In this case, said compounds are preferably selectedfrom monoarylamines, as defined above.

It is further preferable that the OLED comprises the material of theinvention in a layer directly adjoining the anode.

More preferably, the OLED of the invention comprises one of thefollowing layer structures:

a) anode—layer comprising the material of the invention—electron blockerlayer—emitting layer;b) anode—layer comprising the material of the invention—hole transportlayer—electron blocker layer—emitting layer;c) anode—first layer comprising the material of the invention—holetransport layer—second layer comprising the material of theinvention—electron blocker layer—emitting layer.

Those layers that preferably adjoin the emitting layer on the cathodeside correspond to the abovementioned preferred layers in thesepositions, namely one or more hole blocker layers, electron transportlayers and electron injection layers.

In structure a), it is possible for both the layer comprising thematerial of the invention and the electron blocker layer to comprise thesame compound of the formula (A). In structure c), both the layercomprising the material of the invention and the hole transport layermay comprise the same compound of the formula (A) and/or both the secondlayer comprising the material of the invention and the electron blockerlayer may comprise the same compound of the formula (A).

It is preferable when the material of the invention is used in an OLEDcomprising one or more phosphorescent emitting compounds. The term“phosphorescent emitting compounds” typically encompasses compoundswhere the emission of light is effected through a spin-forbiddentransition, for example a transition from an excited triplet state or astate having a higher spin quantum number, for example a quintet state.

Suitable phosphorescent emitting compounds (triplet emitters) areespecially compounds which, when suitably excited, emit light,preferably in the visible region, and also contain at least one atom ofatomic number greater than 20, preferably greater than 38, and less than84, more preferably greater than 56 and less than 80. Preferredphosphorescent emitting compounds are compounds containing copper,molybdenum, tungsten, rhenium, ruthenium, osmium, rhodium, iridium,palladium, platinum, silver, gold or europium, especially compoundscontaining iridium, platinum or copper. In the context of the presentinvention, all luminescent iridium, platinum or copper complexes areconsidered to be phosphorescent emitting compounds.

Examples of the above-described emitting compounds can be found inapplications WO 00/70655, WO 01/41512, WO 02/02714, WO 02/15645, EP1191613, EP 1191612, EP 1191614, WO 05/033244, WO 05/019373 and US2005/0258742. In general, all phosphorescent complexes as used forphosphorescent OLEDs according to the prior art and as known to thoseskilled in the art in the field of organic electroluminescent devicesare suitable. It is also possible for the person skilled in the art,without exercising inventive skill, to use further phosphorescentcomplexes in combination with the material of the invention in an OLED

In an alternative embodiment, it is preferable that the material is usedin an OLED comprising a fluorescent emitting compound in its emittinglayer. Preferably, the emitting layer in this case comprises anarylamino compound as fluorescent emitting compound, more preferably incombination with a host material. The host material in this case ispreferably selected from compounds comprising one or more anthracenegroups.

Preferred embodiments of the different functional materials in theelectronic device are listed hereinafter.

Preferred phosphorescent emitting compounds are the abovementionedcompounds.

Preferred fluorescent emitting compounds are selected from the class ofthe arylamines. An arylamine or an aromatic amine in the context of thisinvention is understood to mean a compound containing three substitutedor unsubstituted aromatic or heteroaromatic ring systems bonded directlyto the nitrogen. Preferably, at least one of these aromatic orheteroaromatic ring systems is a fused ring system, more preferablyhaving at least 14 aromatic ring atoms. Preferred examples of these arearomatic anthraceneamines, aromatic anthracenediamines, aromaticpyreneamines, aromatic pyrenediamines, aromatic chryseneamines oraromatic chrysenediamines. Further preferred emitting compounds areindenofluoreneamines or -diamines, for example according to WO2006/108497 or WO 2006/122630, benzoindenofluoreneamines or -diamines,for example according to WO 2008/006449, and dibenzoindenofluoreneaminesor -diamines, for example according to WO 2007/140847, and theindenofluorene derivatives having fused aryl groups disclosed in WO2010/012328. Likewise preferred are the pyrenearylamines disclosed in WO2012/048780 and in WO 2013/185871. Likewise preferred are thebenzoindenofluoreneamines disclosed in WO 2014/037077, thebenzofluoreneamines disclosed in WO 2014/106522 and the extendedbenzoindenofluorenes disclosed in WO 2014/111269.

Useful matrix materials, preferably for fluorescent emitting compounds,include materials of various substance classes. Preferred matrixmaterials are selected from the classes of the oligoarylenes (e.g.2,2′,7,7′-tetraphenylspirobifluorene according to EP 676461 ordinaphthylanthracene), especially of the oligoarylenes containing fusedaromatic groups, the oligoarylenevinylenes (e.g. DPVBi or spiro-DPVBiaccording to EP 676461), the polypodal metal complexes (for exampleaccording to WO 2004/081017), the hole-conducting compounds (for exampleaccording to WO 2004/058911), the electron-conducting compounds,especially ketones, phosphine oxides, sulphoxides, etc. (for exampleaccording to WO 2005/084081 and WO 2005/084082), the atropisomers (forexample according to WO 2006/048268), the boronic acid derivatives (forexample according to WO 2006/117052) or the benzanthracenes (for exampleaccording to WO 2008/145239). Particularly preferred matrix materialsare selected from the classes of the oligoarylenes comprisingnaphthalene, anthracene, benzanthracene and/or pyrene or atropisomers ofthese compounds, the oligoarylenevinylenes, the ketones, the phosphineoxides and the sulphoxides. Very particularly preferred matrix materialsare selected from the classes of the oligoarylenes comprising,anthracene, benzanthracene, benzophenanthrene and/or pyrene oratropisomers of these compounds. An oligoarylene in the context of thisinvention shall be understood to mean a compound in which at least threearyl or arylene groups are bonded to one another.

Preferred matrix materials for phosphorescent emitting compounds arearomatic ketones, aromatic phosphine oxides or aromatic sulphoxides orsulphones, for example according to WO 2004/013080, WO 2004/093207, WO2006/005627 or WO 2010/006680, triarylamines, carbazole derivatives,e.g. CBP (N,N-biscarbazolylbiphenyl) or the carbazole derivativesdisclosed in WO 2005/039246, US 2005/0069729, JP 2004/288381, EP 1205527or WO 2008/086851, indolocarbazole derivatives, for example according toWO 2007/063754 or WO 2008/056746, indenocarbazole derivatives, forexample according to WO 2010/136109, WO 2011/000455 or WO 2013/041176,azacarbazole derivatives, for example according to EP 1617710, EP1617711, EP 1731584, JP 2005/347160, bipolar matrix materials, forexample according to WO 2007/137725, silanes, for example according toWO 2005/111172, azaboroles or boronic esters, for example according toWO 2006/117052, triazine derivatives, for example according to WO2010/015306, WO 2007/063754 or WO 2008/056746, zinc complexes, forexample according to EP 652273 or WO 2009/062578, diazasilole ortetraazasilole derivatives, for example according to WO 2010/054729,diazaphosphole derivatives, for example according to WO 2010/054730,bridged carbazole derivatives, for example according to US 2009/0136779,WO 2010/050778, WO 2011/042107, WO 2011/088877 or WO 2012/143080,triphenylene derivatives, for example according to WO 2012/048781, orlactams, for example according to WO 2011/116865 or WO 2011/137951.

Suitable charge transport materials as usable in the hole injection orhole transport layer or electron blocker layer or in the electrontransport layer of the electronic device of the invention are, as wellas the compounds of the formula (A), for example, the compoundsdisclosed in Y. Shirota et al., Chem. Rev. 2007, 107(4), 953-1010, orother materials as used in these layers according to the prior art.

Examples of preferred materials which can be used in a hole transport,hole injection or electron blocker layer in the electroluminescentdevice of the invention are, as well as the compounds of the formula(A), indenofluorenamine derivatives (for example according to WO06/122630 or WO 06/100896), the amine derivatives disclosed in EP1661888, hexaazatriphenylene derivatives (for example according to WO01/049806), amine derivatives having fused aromatic systems (for exampleaccording to U.S. Pat. No. 5,061,569), the amine derivatives disclosedin WO 95/09147, monobenzoindenofluoreneamines (for example according toWO 08/006449), dibenzoindenofluoreneamines (for example according to WO07/140847), spirobifluoreneamines (for example according to WO2012/034627 and WO 2013/120577), fluoreneamines (for example accordingto WO 2014/015937, WO 2014/015938 and WO 2014/015935),spirodibenzopyranamines (for example according to WO 2013/083216) anddihydroacridine derivatives (for example according to WO 2012/150001).

Materials used for the electron transport layer may be any materials asused according to the prior art as electron transport materials in theelectron transport layer. Especially suitable are aluminium complexes,for example Alq₃, zirconium complexes, for example Zrq₄, lithiumcomplexes, for example Liq, benzimidazole derivatives, triazinederivatives, pyrimidine derivatives, pyridine derivatives, pyrazinederivatives, quinoxaline derivatives, quinoline derivatives, oxadiazolederivatives, aromatic ketones, lactams, boranes, diazaphospholederivatives and phosphine oxide derivatives.

Preferred cathodes of the electronic device are metals having a low workfunction, metal alloys or multilayer structures composed of variousmetals, for example alkaline earth metals, alkali metals, main groupmetals or lanthanoids (e.g. Ca, Ba, Mg, Al, In, Mg, Yb, Sm, etc.).Additionally suitable are alloys composed of an alkali metal or alkalineearth metal and silver, for example an alloy composed of magnesium andsilver. In the case of multilayer structures, in addition to the metalsmentioned, it is also possible to use further metals having a relativelyhigh work function, for example Ag or Al, in which case combinations ofthe metals such as Ca/Ag, Mg/Ag or Ba/Ag, for example, are generallyused. It may also be preferable to introduce a thin interlayer of amaterial having a high dielectric constant between a metallic cathodeand the organic semiconductor. Examples of useful materials for thispurpose are alkali metal or alkaline earth metal fluorides, but also thecorresponding oxides or carbonates (e.g. LiF, Li₂O, BaF₂, MgO, NaF, CsF,Cs₂CO₃, etc.). It is also possible to use lithium quinolinate (LiQ) forthis purpose. The layer thickness of this layer is preferably between0.5 and 5 nm.

Preferred anodes are materials having a high work function. Preferably,the anode has a work function of greater than 4.5 eV versus vacuum.Firstly, metals having a high redox potential are suitable for thispurpose, for example Ag, Pt or Au. On the other hand, metal/metal oxideelectrodes (e.g. Al/Ni/NiO_(x), Al/PtO_(x)) may also be preferred. Forsome applications, at least one of the electrodes has to be transparentor partly transparent in order to enable the irradiation of the organicmaterial (organic solar cell) or the emission of light (OLED, O-LASER).Preferred anode materials here are conductive mixed metal oxides.Particular preference is given to indium tin oxide (ITO) or indium zincoxide (IZO). Preference is further given to conductive doped organicmaterials, especially conductive doped polymers. In addition, the anodemay also consist of two or more layers, for example of an inner layer ofITO and an outer layer of a metal oxide, preferably tungsten oxide,molybdenum oxide or vanadium oxide.

The device is structured appropriately (according to the application),contact-connected and finally sealed, in order to rule out damagingeffects by water and air.

In a preferred embodiment, the electronic device is characterized inthat one or more layers are coated by a sublimation process. In thiscase, the materials are applied by vapour deposition in vacuumsublimation systems at an initial pressure of less than 10⁻⁵ mbar,preferably less than 10⁻⁶ mbar.

In this case, however, it is also possible that the initial pressure iseven lower, for example less than 10⁻⁷ mbar. Preferred methods forapplication of layers from the gas phase are described further up, andapply generally to the production of layers in the OLEDs of theinvention.

In an alternative embodiment, the electronic device is characterized inthat one or more layers are applied from solution. Preferred methods forapplication of layers from solution are described further up, and applygenerally to the production of layers in the OLEDs of the invention.

The OLEDs of the invention can be used in displays, as light sources inlighting applications and as light sources in medical and/or cosmeticapplications (for example light therapy).

WORKING EXAMPLES A) Syntheses 1) Synthesis of BiC

50 g (113.56 mmol) of triphenylbismuthane (CAS No.: 603-33-8) and 89.40g of 3,5-bis(trifluoromethyl)benzoic acid (340.36 mmol) are initiallycharged in a flask inertized under argon and 1 l of dried toluene isadded. The mixture is heated gradually to 80° C. and then stirred atthis temperature for a further 12 hours. The mixture is subsequentlycooled to room temperature and filtered through a protective gas frit,washed three times with toluene, dried at the vacuum pump and thensublimed under high vacuum.

2) Synthesis of bismuth tris(pentafluorobenzoate) Bi[OOC—C₆F₅]₃(BipFBz=BiC1)

The synthesis proceeds analogously to the above synthesis, withcorresponding use of pentafluorobenzoic acid as ligand rather than3,5-bis-(trifluoromethyl)benzoic acid.

B) Conductivity Measurements

The compounds DA1 and MA1 are each coevaporated with one of the dopantsBiC and BipFBz (for structures see Table 2 below) in proportions byvolume between 1% by volume and 15% by volume. This produces differentlayer thicknesses.

Subsequently, the specific conductivities of the layers are measured.For this purpose, the following method is used:

The conductivity of the doped layers is determined by means of what iscalled a finger structure. This involves two intermeshing structured ITOelectrodes shaped like fingers. Between the finger electrodes is the(doped) organic layer having a thickness d. The gap width between theelectrodes has the value S. A safety margin between the supply and theITO electrodes ensures that the current measured results from thecurrent flow between the ITO fingers. I(U) (current-voltagecharacteristic) is measured for various values of S (typically a few μm)and d (typically 120 nm). From this, it is possible to unambiguouslydetermine the conductivity of doped layers by the following formula:

$\sigma = {\frac{I}{L \cdot d} \cdot \frac{S}{U}}$

The advantage of this method over a metal-doped layer/ITO constructionis that the ohmic behaviour is extended over a wide voltage range andthe two contacts consist of the same material, such that the barrierheights for charge carrier injection between contact and organic areidentical in forward and reverse direction. The values obtained for thespecific conductivity are plotted in FIG. 1 against the proportion byvolume of the dopant, in each case for the following host/dopantcombinations: i) BipFBz (═BiC1): DA1; ii) BipFBz (═BiC1): MA1; iii) BiC:DA1; and iv) BiC: MA1. Inventive combinations are ii) and iv).

It is found that the desired specific conductivities of between 10⁻⁴ S/mand 10⁻³ S/m, in the inventive cases, can be achieved within a widerange between 5% and 14% by volume. Dopant concentrations in the rangebetween 5% and 14% by volume are practical and can be establishedeasily.

A particular advantage of the inventive Bi dopants BiC and BipFBz isthat it is thus possible to dope not only hole transport materialshaving a high-lying HOMO, such as DA1 (HOMO about −4.83 eV) but alsohole transport materials having a low-lying HOMO such as MA1 (HOMO about−5.18 eV) to the desired specific conductivity (see combinations ii) andiv) above with the hole transport material MA1). The use of holetransport materials with a low-lying HOMO is highly desirable becausethis dispenses with the necessity of inserting a further layer having alow HOMO between the hole transport layer and emitting layer. Thisenables a simpler construction of the OLED and hence a more efficientproduction process.

C) Measurement of the Absorption Properties of the Dopants of theInvention

The host/dopant combinations ii) and iv) specified in B) and theNDP-2:NHT-5 combination (2% by volume of NDP-2) according to the priorart are analysed for their absorption in the VIS range. It is found thatthe inventive combinations comprising Bi dopants have only a lowabsorption in the VIS range. In contrast, for the combination ofmaterials NHT-5 and NDP-2 according to prior art, an absorption band isobserved in the visible region with an absorption maximum at about 500nm. The absence of significant absorption bands in the visible region isan important use advantage of the inventive combinations of holetransport materials with Bi dopants. Absorptions in the VIS range affectthe emission characteristics of the OLED and worsen the efficiencythereof.

D) Device Examples

In examples I1 to 14 and C1 to C4 which follow, the data of variousOLEDs are presented. Examples C1 to C4 are comparative examplesaccording to the prior art; examples I1 to I4 show data of OLEDs of theinvention.

OLEDs of the invention and OLEDs according to the prior art are producedby a general method according to WO 2004/058911, which is adapted to thecircumstances described here (variation in layer thickness, materials).Glass plaques which have been coated with structured ITO (indium tinoxide) in a thickness of 50 nm are the substrates for the OLEDs. Thesubstrates are subjected to wet cleaning (cleaning machine, detergent:Merck Extran), then baked at 250° C. for 15 min and, prior to thecoating, treated with an oxygen plasma.

Various layers are applied to the pretreated substrates: first holetransport layer (HTL1)/second hole transport layer (HTL2)/optional thirdhole transport layer (HTL3)/emission layer (EML)/electron transportlayer (ETL)/electron injection layer (EIL) and finally a 100 nm-thickaluminium cathode. The exact structure of the OLEDs can be found inTable 1. The materials used for production of the OLEDs are shown inTable 2.

All materials are applied by thermal vapour deposition in a vacuumchamber. In this case, the emission layer always consists of at leastone matrix material and an emitting compound which is added to thematrix material(s) in a particular proportion by volume byco-evaporation. Details given in such a form as M1:D1 (95%:5%) mean herethat the material M1 is present in the layer in a proportion by volumeof 95% and D1 in a proportion by volume of 5%. Analogously, the electrontransport layer may also consist of a mixture of two materials.

The OLEDs are characterized in a standard manner. For this purpose, theelectroluminescence spectra and the external quantum efficiency (EQE,measured in percent) are determined as a function of luminance,calculated from current-voltage-luminance characteristics (IULcharacteristics) assuming Lambertian radiation characteristics, and thelifetime. The electroluminescence spectra are determined at a luminanceof 1000 cd/m², and the CIE 1931 x and y color coordinates are calculatedtherefrom. The lifetime LT80 is defined as the time after which theluminance drops from the starting luminance to 80% of the start value inthe course of operation with constant current density.

TABLE 1 Structure of the OLEDs HTL1 HTL2 HTL3 EML ETL EIL Ex. thicknessthickness thickness thickness thickness thickness C1 MA1: MA1: MA1 M1:D1ST1:LiQ LiQ F4TCNQ F4TCNQ 20 nm (95%:5%) (50%:50%) 1 nm (95%:5%)(95%:5%) 20 nm 30 nm 20 nm 155 nm C2 MA1: MA1 MA1 M1:D1 ST1:LiQ LiQF4TCNQ 155 nm 20 nm (95%:5%) (50%:50%) 1 nm (95%:5%) 20 nm 30 nm 20 nmC3 NPB:BiC NPB M1:D1 ST1:LiQ LiQ (95%:5%) 180 NM (95%:5%) (50%:50%) 1 nm20 nm 20 nm 30 nm C4 DA1:BiC DA2 M1:D1 ST1:LiQ LiQ (95%:5%) 180 nm(95%:5%) (50%:50%) 1 nm 20 nm 20 nm 30 nm I1 MA1:BiC MA1:BiC MA1 M1:D1ST1:LiQ LiQ (95%:5%) (95%:5%) 20 nm (95%:5%) (50%.50%) 1 nm 20 nm 155 nm20 nm 30 nm I2 MA1:B1C MA1 MA1 M1:D1 ST1:LiQ LiQ (95%:5%) 155 nm 20 nm(95%:5%) (50%:50%) 1 nm 20 nm 20 nm 30 nm I3 MA1:BiC MA1 M1:D1 ST1:LiQLiQ (95%:5%) 180 nm (95%:5%) (50%:50%) 1 nm 20 nm 20 nm 30 nm I4 MA3:BiCMA3 M1:D1 ST1:LiQ LiQ (95%:5%) 180 nm (95%:5%) (50%:50%) 1 nm 20 nm 20nm 30 nm

TABLE 2 Structural formulae of the materials for the OLEDs

Commercially available (Novaled) NDP-2 Commercially available (Novaled)NHT-5

The examples are elucidated in detail hereinafter, in order toillustrate the advantages of the OLEDs of the invention.

Example 1

Inventive sample I1 is compared with comparative sample C1. The formerdiffers from C1 in that it contains the p-dopant BiC rather than thep-dopant F4TCNQ in HTL1 and HTL2. Comparison of I1 and C1 shows a muchlower leakage current at an applied voltage of 1 V of 7.9 E-6 mA/cm²compared to 1.6 E-4 mA/cm² with the present sample geometry and a pixelsize of 2×2 mm². Leakage currents are understood to mean current flowsbetween the anode and cathode which do not flow through the organiclayers of the OLED. One of their causes may be a high lateralconductivity in the p-doped layer of the OLED. Leakage currents are agreat problem with decreasing pixel size in displays, since they canlead to crosstalk between the pixels.

Example 2

Inventive sample I2 is compared with comparative sample C2. The formerdiffers from C2 in that it contains the p-dopant BiC rather than thep-dopant F4TCNQ in HTL1. Comparison of 12 and C2 shows a comparablevoltage of the two samples of 3.8 V @ 10 mA/cm². However, the efficiencyis much higher in the case of 12 (8.9% EQE @ 10 mA/cm²) as compared withthe comparative sample C2 (8.5% EQE @ 10 mA/cm²). The lifetime of thetwo samples is about 300 h LT80 @ 60 mA/cm².

Example 3

Inventive sample I4 is compared with comparative samples C3 and C4. Theformer differs from C3 and C4 in that it contains a specific compound offormula (A) as material for the HTL, and not the hole-transportingcompounds known from the prior art. The p-dopant BiC is always used inthe first of the two hole-transporting layers present. Inventive sampleI4 has a better lifetime and efficiency than the comparative samples C3and C4 (Table 3), with similar values for voltage.

TABLE 3 Results for the OLEDs Ex. U @ 10 mA/cm² EQE @ 10 mA/cm² LT80 @60 mA/cm² C3 4.3 5.7 195 C4 3.8 4.1 50 I4 4.1 8.1 355

The examples shown illustrate the advantages of the inventivecombination of bismuth complexes with compounds of the formula (A) ashole transport materials in OLEDs. They should not be interpreted in arestrictive manner. The advantages of the inventive combination extendover the whole scope of the material combinations defined in the claims.

E) Quantum-Chemical Method for Determination of Orbital Energies

The HOMO and LUMO energies of the materials are determined viaquantum-chemical calculations. In this present case, the softwarepackage “Gaussian09, Revision D.01” (Gaussian Inc.) is used. Forcalculation of organic substances without metals (referred to as the“org.” method), a geometry optimization is first conducted by thesemi-empirical method AM1 (Gaussian input line “# AM1 opt”) with charge0 and multiplicity 1. Subsequently, on the basis of the optimizedgeometry, a single-point energy calculation is effected for theelectronic ground state and the triplet level. This is done using theTDDFT (time dependent density functional theory) method B3PW91 with the6-31G(d) basis set (Gaussian input line “# B3PW91/6-31G(d)td=(50-50,nstates=4)”) (charge 0, multiplicity 1). For organometalliccompounds (referred to as the “M-org.” method), the geometry isoptimized by the Hartree-Fock method and the LanL2 MB basis set(Gaussian input line “# HF/LanL2 MB opt”) (charge 0, multiplicity 1).The energy calculation is effected, as described above, analogously tothat for the organic substances, except that the “LanL2DZ” basis set isused for the metal atom and the “6-31G(d)” basis set for the ligands(Gaussian input line “#B3PW91/gen pseudo=lanl2 td=(50−50,nstates=4)”).From the energy calculation, the HOMO is obtained as the last orbitaloccupied by two electrons (alpha occ. eigenvalues) and LUMO as the firstunoccupied orbital (alpha virt. eigenvalues) in Hartree units, where HEhand LEh represent the HOMO energy in Hartree units and the LUMO energyin Hartree units respectively. This is used to calculate the HOMO andLUMO value in electron volts, calibrated by cyclic voltammetrymeasurements, as follows:

HOMO(eV)=((HEh*27.212)−0.9899)/1.1206

LUMO(eV)=((LEh*27.212)−2.0041)/1.385

These values are to be regarded as HOMO and as LUMO of the materials inthe context of this application.

The method described herein is independent of the software package usedand always gives the same results. Examples of frequently utilizedprograms for this purpose are “Gaussian09” (Gaussian Inc.) and Q-Chem4.1 (Q-Chem, Inc.). In the present case, the energies are calculatedusing the software package “Gaussian09, Revision D.01”.

1.-19. (canceled)
 20. A material comprising a compound A of a formula(A)

where the variables that occur are: Z is CR¹; Ar¹ is the same ordifferent at each instance and is an aromatic ring system which has 6 to30 aromatic ring atoms and is optionally substituted by one or more R¹radicals, or a heteroaromatic ring system which has 5 to 30 aromaticring atoms and is optionally substituted by one or more R¹ radicals; Ar¹groups here is optionally bonded to one another via R¹ radicals; R¹ isthe same or different at each instance and is selected from H, D, F,C(═O)R², CN, Si(R²)₃, P(═O)(R²)₂, OR², S(═O)R², S(═O)₂R², straight-chainalkyl or alkoxy groups having 1 to 20 carbon atoms, branched or cyclicalkyl or alkoxy groups having 3 to 20 carbon atoms, alkenyl or alkynylgroups having 2 to 20 carbon atoms, aromatic ring systems having 6 to 30aromatic ring atoms, and heteroaromatic ring systems having 5 to 30aromatic ring atoms; where two or more R¹ radicals is optionally joinedto one another and may form a ring; where the alkyl, alkoxy, alkenyl andalkynyl groups mentioned and the aromatic ring systems andheteroaromatic ring systems mentioned may each be substituted by one ormore R² radicals; and where one or more CH₂ groups in the alkyl, alkoxy,alkenyl and alkynyl groups mentioned is optionally replaced by—R²C═CR²—, —C≡C—, Si(R²)₂, C═O, C═NR², —C(═O)O—, —C(═O)NR²—, P(═O)(R²),—O—, —S—, SO or SO₂; R² is the same or different at each instance and isselected from H, D, F, CN, alkyl groups having 1 to 20 carbon atoms,aromatic ring systems having 6 to 30 aromatic ring atoms andheteroaromatic ring systems having 5 to 30 aromatic ring atoms; wheretwo or more R² radicals is optionally joined to one another and may forma ring; and where the alkyl groups, aromatic ring systems andheteroaromatic ring systems mentioned is optionally substituted by F orCN; and a compound P which is a complex of bismuth.
 21. The materialaccording to claim 20, wherein the compound A does not contain a fusedaryl group having more than 10 aromatic ring atoms nor a fusedheteroaryl group having more than 14 aromatic ring atoms.
 22. Thematerial according to claim 20, wherein, in the compound A, the Ar¹group is the same or different at each instance and is an aromatic ringsystem which has 6 to 24 aromatic ring atoms and is optionallysubstituted by one or more R¹ radicals, or a heteroaromatic ring systemwhich has 5 to 24 ring atoms and is optionally substituted by one ormore R¹ radicals.
 23. The material according to claim 20, wherein, inthe compound A, the Ar¹ group is a group which is optionally substitutedby one or more R¹ radicals and is selected from the group consisting ofphenyl, biphenyl, terphenyl, quaterphenyl, naphthyl, phenanthryl,fluoranthenyl, fluorenyl, indenofluorenyl, spirobifluorenyl,dibenzofuranyl, dibenzothiophenyl, carbazolyl, acridyl andphenanthridyl.
 24. The material according to claim 20, wherein thecompound P is a complex of bismuth in the (III) oxidation state.
 25. Thematerial according to claim 20, wherein the compound P is a complex ofbismuth having at least one ligand L which is an organic compound. 26.The material according to claim 25, wherein the ligand L is singlynegatively charged.
 27. The material according to claim 25, wherein thegroup in the ligand L that binds to the bismuth atom is selected fromthe group consisting of carboxylic acid groups, thiocarboxylic acidgroups, carboxamide groups and carboximide groups.
 28. The materialaccording to claim 25, wherein the ligand L is selected from fluorinatedbenzoic acid derivatives, fluorinated or non-fluorinated phenylaceticacid derivatives and fluorinated or non-fluorinated acetic acidderivatives.
 29. The material according to claim 20, wherein thecompound P is present in the material as a dopant in a concentration of0.1% to 30%.
 30. A layer for use in an electronic device, comprising thematerial according to claim
 20. 31. A formulation comprising thematerial according to claim 20 and at least one solvent.
 32. A processfor producing a layer according to claim 30, which comprises applyingcompound A and compound P together from the gas phase.
 33. A process forproducing a layer which comprises applying a formulation comprising thematerial according to claim 20 and a solvent from the liquid phase. 34.An electronic device selected from organic electroluminescent devices,organic integrated circuits, organic field-effect transistors, organicthin-film transistors, organic light-emitting transistors, organic solarcells, organic optical detectors, organic photoreceptors, organicfield-quench devices, organic light-emitting electrochemical cells andorganic laser diodes, comprising a material according to claim
 20. 35.The organic electroluminescent device according to claim 34, wherein thedevice includes the material in a hole-transporting layer disposedbetween anode and emitting layer, with one or more further layerspresent between the layer comprising the material and the emittinglayer.
 36. The organic electroluminescent device according to claim 35,wherein the HOMO levels of the hole-transporting layer (HTL) and the onelayer between hole-transporting layer and emitting layer (EBL) meet thefollowing condition:HOMO(HTL)<=HOMO(EBL).
 37. The organic electroluminescent deviceaccording to claim 35, wherein the one or more further layers disposedbetween the layer comprising the material and the emitting layercomprise one or more identical or different compounds of the formula(A).
 38. The organic electroluminescent device according to claim 34,wherein the device comprises the material in a layer directly adjoiningthe anode.